1. Field of the Invention
This invention relates to technology by which juice beverages are hot filled into small-sized polymeric containers. More particularly, the invention relates to hot filling of juices into individual-serving sized polymeric containers and ensuring beverage wholesomeness through the use of a post-filling heat dwell procedure. The invention has special application for citrus beverages.
2. Description of Related Art
A wide variety of food products are packaged by so-called hot filling of the food product into a polymeric container which then is capped and allowed to cool to a product which can be subjected to shelf storage at ambient temperatures. Certain hot-filled food products are of a so-called high-acid type, typically meaning that the product has a pH of less than 4.6. In general, the hot filling of products has the benefit of raising the temperature of the food product being filled, as well as of the portions of the container being filled which are contacted by the heated food product. Being thus contacted by the heated food has the benefit of addressing the need for aseptic or sterile filling.
For example, hot-filled food products and beverages with a pH of less than 4.6 are heated in continuous systems for effecting microbial control for the particular food or beverage. The relatively low pH helps to control microbial growth, which is useful in combination with heating and contacting with heated materials to help control microbial growth in the bottled product. Usually such processes are adequate to provide a wholesome product for an extended shelf life at ambient temperature. For such products, storage under refrigerated conditions is not essential for providing a product with extended shelf life.
When the food product is a citrus juice beverage, particular problems surface due to the solids content of citrus juices. This is especially the case for citrus juice beverages which are 100% citrus juice. Beside such whole juice products, beverages containing a substantial percentage of citrus juice encounter similar problems. In a typical filling system for a beverage that is not particularly natural or viscous, so-called flood filling techniques are used. By these techniques, the beverage is filled very close to the top of the container, over filling it in some circumstances. Because such products are not particularly viscous or highly solids containing, there is little concern if some of the beverage flows over or splashes onto the outside of the bottles when the containers are moved prior to capping.
This flood filing approach is not a viable option for the type of products filled according to the invention. With such products, overfilled or splashed out beverage leaves a solid residue that turns into an unsightly and a potentially unsanitary residue on the outside of the container. This difficulty is compounded when the bottles being filled have a low-volume capacity, such as 12 fluid oz. or less. If a typical small-volume container is filled close to its top sealing surface (TSS), centrifugal forces when the bottles move on the bottle handling line will tend to spill the contents out of the relatively small bottles. This creates a potential need to have the hot product as close as possible to the TSS for aseptic reasons, but spaced from the TSS to address the spill over problem. It is important that the package finish be subjected to proper and adequate heat treatment without having a residue left thereon.
It will be appreciated that low fill levels are required for juices, especially those which are highly viscous or have a relatively high solids content. When compared with flood filling approaches, heat loss is higher for low fill level approaches. The combination of low fill level with a smaller container itself creates a problem of how to achieve proper heat treatment without using excessive heating which can damage the juice or damage or misshape the package finish area which typically contains threads for receiving a cap. The container bell and top sealing surface can experience excessive shrinkage if subjected to too high a temperature for too long a time.
In a hot filling line, it is important that the heated food product be in contact with the inside of the container, including the package finish area, for a time adequate to ensure sterilization. When the container being filled is of a larger volume than those under consideration here, the latent heat of such a larger volume of beverage ensures that the elevated temperature will be maintained for a time adequate to ensure that microbial issues are properly addressed. Somewhat similarly, when the container or bottle being filled has a thickness such that it provides a good thermal barrier, that thermal barrier will be counted upon to be adequate to maintain the heat as required for good manufacturing practices.
In fact, when a bottle has a relatively small volume, resistance to bottle deformation at a higher filling temperature intuitively should be addressed by providing a thicker wall. However, a thicker wall means that more material is needed for each bottle, thereby increasing cost. Increased wall thickness for a small bottle of 12 fluid ounces or less is particularly cost inefficient. These relatively high costs due to a thick-walled container have been found to be so costly on a unit basis that such small volume beverages would have to be sold at prices which are too high to be competitive.
Another problem which has come to be appreciated in developing this invention relates to polymer materials. A polymer which is often advantageous for beverage bottles is polyethylene terephthalate (PET). Another popular polymer for these types of products is high density polyethylene. Polymers such as these, and particularly PET, tend to be heat sensitive in the face of high temperatures for extended time periods. PET, for example, has a tendency to start to crystallize and flow under such conditions. Such considerations further suggest a thicker wall is desirable when the polymer has properties which, after being molded into a bottle, can change negatively upon exposure to temperatures above normal acidic beverage hot fill temperatures, which is the case for PET, for example.
Heretofore it has been suggested that hot water baths, hot water sprays, and/or steam sprays could be beneficial in addressing those situations where a relatively small latent heat of the hot filled food and its combination with preferred thin polymer wall thickness are not adequate to maintain the proper elevated temperature for the needed length of time in order to ensure all microbial issues have been fully and adequately handled. The invention realizes that these types of liquid or water based heat application systems bring with them their own problems for small polymeric bottles. Such applications are unsatisfactory for a variety of reasons. Hot water/steam presents a clean-up problem and can be a potential source of contamination. Also, having a hot spray impinge upon relatively small and delicate bodies potentially causes bottle damage. In addition, these types of sprays provide inconsistent heat transfer depending upon varied spray projections with respect to different bottles in the line. For example, different sides of the bottles typically encounter different quantities of water impinging the bottles at different angles. Also, changes in spray rate, angle or pressure will cause inconsistencies and the potential for bottle damage, breach of capped bottle integrity, or inadequate heat application.
These various approaches do not address all of the problems which have arisen by the present attempts to have a stream of relatively small bottles be hot filled and maintained at an adequate temperature throughout the interior of the bottle for a dwell time and temperature which are adequate to ensure sufficient application of heat and resulting control of microbial development upon shelf storage. There is accordingly a need for an approach which is more effective than those currently available in the processing of hot filled beverages in small containers, especially beverages having substantial quantities of citrus juice.